We propose a pilot feasibility trial of a new method for monitoring brain oxygen supply in acute stroke. We intend to apply the recent discovery by Jobsis that redox state of cytochrome a, a3, hemoglobin oxygenation, and relative blood volume can be monitored continuously, regionally, and non invasively through the intact skull, utilizing a portable syytem which does not require radioactive materials. We propose to do this within an established stroke research center which has had a long interest in he clinical problem of acute and progressive stroke, and which has maintained a sustained effect at developing methods for monitoring the regional circulatory abnormality in acute stroke. We have done and continue to do this with substantial background and ongoing solid clinical and experimental experience with the cerebral circulation. Although the proposed method itself is new to us, we are assured of the active consultative advice and support of the developer of the method, Dr. Frans Jobsis. If this method is proved feasible it will be possible to move on to rapid development of a continuous multiregional monitoring system for stroke and head injury intensive care in which the primary emphasis is on the focal ischemic lesion. This should have an impact comparable to that in cardiac intensive care resulting from continuous monitoring of the electrocardiogram and introduction of the Swann-Ganz catheter.